As semiconductor devices are scaled to smaller sizes, new materials and concepts are being considered to meet advanced performance targets. Processing conditions at each step are also extremely important for controlling the quality of the semiconductor devices.
Chemical vapor deposition (CVD) is a process for forming stable solids by decomposition of gaseous chemical using heat, plasma, ultraviolet, or other energy sources, or combinations thereof. Reactant gases are passed over a wafer, causing CVD of a thin layer of the reactant material on the wafer. For example, epitaxial growth of silicon can be achieved by CVD using heat as the energy source for decomposing one or more gaseous chemicals. The temperature in the CVD process can affect growth rate and morphology of the deposited product. Various process conditions, e.g. temperature uniformity and reactant gas distribution, must be carefully controlled to ensure high quality of the deposited layers and resulting semiconductor devices.